How come reflections are still visible using 0 bounces?
Light paths inherit the proprety after the first bounce
Short answer is that the bounces number is not referring to the occoured light bounces but only to the &quot;diffuse/glossy/transparency reflection  bounces&quot; as said in the tooltips:

The manual define the light paths as the following:

Reflection and transmission rays can further have these properties:

Diffuse: the ray is generated by a diffuse reflection or transmission
(translucency).
Glossy: the ray is generated by a glossy specular reflection or transmission.


Imagine the following situation (path tracing actually works the other way around, but let's forget that for a moment):
The photon is emitted by light source, notice that at this moment the ray associated with the photon is &quot;neutral&quot;, it hasn't hit any surface so it can't be defined as &quot;diffuse&quot; or &quot;glossy&quot;, it's just a ray.
Now the photon hits a surface. If the surface is diffusive it generate a Diffuse ray, if it's reflective it generate a Glossy ray. Now, if the Diffuse/Glossy ray is captured from the camera, how times the Diffuse/Glossy ray bounced?
None. It has just been generated. It is visible by the camera, but has bounced none.
The question those numbers are answering can be better phrased as:

How many times are the Diffuse rays allowed to bounce in my scene?


If you picture yourself that the Diffuse rays are the little arrows and not the long one, you'll have an easier time in understanding the values.

Disclaimer: I dunno if it's the whole truth, but it makes sense and I thought it whort sharing my point of view